What are cannabis foxtails and how to manage them?

Cannabis foxtailing is the effect seen when one calyx stacks on top of another forming a thin elongated ‘foxtail’. These are often just a calyx or two wide and a few centimetres (an inch or two) long. Some cannabis breeders have stabilised the foxtail trait for those that enjoy the unusual. But for most other strains, cannabis foxtails may represent lost yield potential. For many home growers, as well as commercial licensed growers, large heavy yielding blooms full of dense THC rich buds is the preferred goal. Learn why cannabis foxtails form and how to detect, prevent and/or manage them.

What is foxtailing in cannabis plants?

Cannabis fox tailing causes your buds to take on an unusual, weird and irregular growth pattern. Instead of the normal chunky buds you are used to, a cannabis foxtail is a long/thin structure caused by a small number of calyxs which grow in a stacked formation. Although the similarities with a real foxes’ tails may be limited, the name has stuck.

What does foxtail weed look like?

As the pictures illustrate, foxtail weed may look unusual and intriguing. The buds will often be resinous and potent. And few can deny the attraction and interest in some of the more esoteric foxtail cannabis strains.

Foxtail weed is often seen in heirloom sativa strains. Many of the best cannabis seed companies hold archived genetics that produce this phenomenon. But demand for seeds of foxtail strains has never been particularly high, mainly due to yield concerns. For that reason, there is limited interest in foxtail-prone strains. Indeed, many growers may feel somewhat alarmed if they see their cannabis buds start to foxtail and may wonder what the remedy is.

Is foxtailing in cannabis plants bad?

Many growers deliberately research their cannabis seeds, often favouring high THC strains with thick, heavy blooms and generous yields. It can feel a disappointment if the promised branch-breaking harvests are replaced with gangly, slender foxtails.

Foxtailing cannabis maybe a desired trait that you enjoy seeing, and your friends will often be impressed to see it. The ‘buds’ may have normal potency levels and great flavour, but most growers prefer to see normal bud formation.

What causes cannabis buds to foxtail?

Cannabis foxtails is sometimes known as a second internode bloom. It may simply be the last ‘hoorah’ from your plants as they approach harvest and squeeze out a few more buds. Yield concerns may be minimal, especially if the foxtails are forming on already-generously proportioned blooms late in the flowering phase. In these circumstances there is little to worry about and you may just want to check that your grow room conditions are within the right limits and continue to allow your plants to reach harvest point.

But sometimes environmental conditions in the grow room itself may have strayed into sub-optimised territory. This can cause plant stress and with it comes the conditions which may cause your normally-fat buds to start fox tailing. In these cases, swift action can limit the yield losses and return your plants to normal growth.

Genetics:

Normally your cannabis seed supplier will indicate if your preferred strain has been deliberately bred to foxtail. Very few commercial varieties are designed like this due to limited interest from growers. But you may see foxtailing especially on some sativa strains, this can happen with either feminised cannabis seeds or autoflower seeds.

Three of Dutch Passion’s sativa strains, Desfrán, Strawberry Cough and Skywalker Haze may occasionally show foxtails, even in good grow conditions. This is simply a genetic trait, meaning there is nothing to worry about if you see the occasional foxtail.

Heat stress:

Heat stress is a known trigger for cannabis fox tailing. Cannabis grows well indoors when the ‘lights-on’ temperatures are around 22-25ºC (around 72ºF - 77ºF). Exceed these temperatures and one of the effects you may see is increased numbers of cannabis fox tails. Those growing cannabis outdoors or in greenhouses may seem the same effect.

Light stress:

If you have pushed your plants above the optical sweet spot in bloom you may also see cannabis fox tails appear. Often light intensities above 1000PPFD (without CO2 supplementation) may be too much for some strains. The stress from light-overload can induce cannabis fox tail formation.

Less experienced growers, or those that have recently invested in powerful LED grow lights may be particularly at risk of this. As are growers that have lights too close to their crops. Yellowing leaves can also be a sign that they are suffering light stress. Combine light stress with cannabis genetics that may be pre-disposed to it and cannabis foxtailing may result.

Many serious growers use a light meter to map the light intensities in their grow room at different light hanging heights. Or they use data from the LED light supplier to determine the optical sweet spot for their plants.

How to fix foxtailing cannabis buds

Assuming that you haven’t deliberately grown a known stabilised foxtail strain, the main approach is to return grow room conditions to optimised conditions as soon as possible. Reduce heat, increase extraction and reduce light intensity. Many LED’s have controllable intensity dials. If not, just raise the height of the light increasing the distance to the canopy.

How to prevent foxtailing buds

You may want to avoid growing in the hottest seasons if you have seen cannabis crops foxtail previously in heatwaves. Those that can afford it will add air-con to the grow room. This allows absolute temperature control in all conditions/seasons and will also allow yield/potency improvements as your plants bloom in optimised conditions.

Those that suspect light stress has contributed to previous cannabis fox tail problems may also want to check with their light manufacturer. Usually, the more competent suppliers will be able to offer accurate charts showing recommended coverage areas and PPFD levels at various hanging heights for different sized grow rooms.

When to harvest foxtailing cannabis buds?

Judge the harvest point as you normally would. Most look for the point when their trichomes are mostly cloudy and take the crop down at that point. Some growers enjoy early-harvested cannabis, with clear trichomes and a lively/energetic high. Others prefer a few red/amber trichomes which may offer a heavier, ‘stonier’ effect.

Dutch Passion’s foxtailing cannabis strains

None of the Dutch Passion strains have been stabilised deliberately to produce fox tail cannabis. Instead, all the strains should produce long, heavy blooms when grown well. But it’s also fair to add that just about any cannabis strain can express fox tail tendencies when the conditions are stressed, especially sativa strains or sativa-dominant phenotypes of a given strain.

Some ‘pure’ sativa strains may express foxtailing in the buds, varieties like Desfrán for example, no matter the circumstances. Skywalker Haze and Strawberry Cough are two other cannabis strains which may sometimes show foxtails, especially in hotter conditions.

Foxtails are equally likely whether you are going from autoflowering cannabis seeds or photoperiod feminised seeds. Causes of cannabis foxtailing vary and may even include sub-surface root rot/damage. But more often, the primary cause of cannabis foxtails is heat stress and/or light stress. Avoid these and the chances are that fox tails won’t be a major headache in your next grow.